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5096/02
HUMAN AND SOCIAL BIOLOGY
Paper 2
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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
General Certificate of Education Ordinary Level
October/November 2007
2 hours
Additional Materials:
Answer Booklet/Paper.
READ THESE INSTRUCTIONS FIRST
If you have been given an Answer Booklet, follow the instructions on the front cover of the Booklet.
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen on both sides of the paper.
Do not use staples, paper clips, highlighters, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Section A
Answer all questions.
Write your answers in the spaces provided on the question paper.
You are advised to spend no longer than 1 hour on Section A.
Section B
Answer all the questions, including questions 8, 9 and 10 Either or 10 Or.
Write your answers to questions 8, 9 and 10 on the separate answer paper
provided.
Write an E (for Either) or an O (for Or) next to the number 10 in the grid below to
indicate which question you have answered.
For Examiner’s Use
1
2
3
4
At the end of the examination fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part
question.
5
6
7
Section A
sub-total
8
9
10
Total
This document consists of 14 printed pages and 2 blank pages.
SPA (NH/CG) T27371/7
© UCLES 2007
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2
Section A
Answer all the questions.
Write your answers in the spaces provided.
1
The three major nutrients are carbohydrates (sugars and starches), lipids (fats and oils) and
proteins. Carbohydrates and lipids contain carbon, hydrogen and oxygen.
(a) Name the additional element in all proteins. .................................................................[1]
(b) Table 1.1 shows the results of some tests carried out on three foods, A, B and C.
Table 1.1
test
Food A
Food B
Food C
add biuret solution
violet solution
violet solution
blue solution
boil with Benedict’s solution
blue solution
blue solution
red solution
add iodine solution
brown colour
brown colour
black colour
rub onto paper, dry
no clear spot
clear spot
no clear spot
Using the information in Table 1.1, state the food or foods that contain
protein, .............................................................................................................................
protein and lipid, ..............................................................................................................
only carbohydrate. .......................................................................................................[4]
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(c) The apparatus shown in Fig. 1.1 can be used to give a measure of the energy content of
a food sample. The sample is fixed onto a mounted needle, set alight and held under the
large tube of water, until it finishes burning. The temperature of the water is taken before
and after burning the food.
For
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stirrer
thermometer
large tube
50g water
mounted needle
burning sample
Fig. 1.1
Explain why the water is stirred before reading the temperature.
......................................................................................................................................[1]
(d) It takes 4.2 joules to raise the temperature of 1 gram of water by 1 °C. In the experiment
shown in Fig. 1.1, the water temperature rose from 20 to 50 °C. Calculate the energy
content in joules of the food sample used.
..........................................................................................................................................
......................................................................................................................................[2]
(e) A student looked up in a textbook the actual energy content of the food used in this
experiment. The energy content was found to be more than twice the value found in the
experiment. How do you explain this?
..........................................................................................................................................
......................................................................................................................................[1]
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(f)
Table 1.2 shows the energy requirements of people of different ages in a warm climate,
measured in kilojoules per kilogram of body mass.
Table 1.2
age / years
energy required / kJ per kg
0–1
460
1–3
420
4–9
340
10–19 female
210
10–19 male
240
25–50 adult female
170
25–50 adult male
190
60–80 elderly male
150
Explain the different energy requirements between the following pairs in the table:
1.
the male at 25–50 and the male at 60–80,
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
2.
the child at 0–1 and that at 4–9,
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
3.
the male at 25–50 and the female at 25–50, even if both are doing the same jobs.
..........................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[4]
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5
(g) Fig. 1.2 shows stages in the digestion of fat in the small intestine.
F
large fat globules
G
tiny fat droplets
fatty acids and
glycerol
Fig. 1.2
(i)
Name substances F and G which bring about the changes shown.
F = ............................................................................................................................
G = ........................................................................................................................[2]
(ii)
Name the organs which make F and G.
F = ............................................................................................................................
G = ........................................................................................................................[2]
(h) Too much fat in the diet can lead to the blocking of arteries by fatty deposits.
Fig. 1.3 shows the heart in exterior view.
H
Fig. 1.3
(i)
Name the arteries labelled H. ...............................................................................[1]
(ii)
Explain why blocking these arteries can cause a heart attack.
..................................................................................................................................
..................................................................................................................................
..............................................................................................................................[2]
[Total: 20]
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2
(a) Fig. 2.1 shows the cycling of nitrogen through a field in which a crop of maize is
growing.
nitrogen (N2) in
the air
denitrification
B
fertilisers
nitrate ions in
the soil
A
nitrate ions in
rivers
uptake from soil
plant proteins
decay
ammonium compounds
crop removed
Fig. 2.1
Name the bacterial processes A and B which increase nitrate ions in the soil.
A = ....................................................................................................................................
B = ................................................................................................................................[2]
© UCLES 2007
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7
(b) Fig. 2.2 shows the effects of increasing quantities of nitrogen fertiliser on crop yield.
Three points have been plotted for you.
6
5
crop yield / tonnes
per hectare
4
3
2
1
0
0
50
100
150
200
250
mass of fertiliser added / kg per hectare
Fig. 2.2
(i)
Complete the graph by using the information in Table 2.1 below.
[1]
Table 2.1
mass of fertiliser added / kg per hectare
crop yield / tonnes per hectare
150
4.7
200
4.8
(ii)
Using Fig. 2.2, describe the effect of adding increasing quantities of nitrogen
fertiliser to this crop.
..................................................................................................................................
..................................................................................................................................
..................................................................................................................................
..............................................................................................................................[3]
[Total: 6]
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8
3
Fig. 3.1 shows a synapse between two neurones.
neurone 1
vesicles of chemical transmitter
synaptic
bulb
cleft
receptors on membrane
of neurone 2
bulb
membrane
neurone 2
mitochondria
Fig. 3.1
When an impulse arrives in neurone 1,
•
vesicles of chemical transmitter fuse with the bulb membrane
•
vesicles release chemical transmitter into the cleft between the two neurones
•
this chemical transmitter diffuses across the cleft
•
chemical transmitter fuses with receptors on the membrane of neurone 2
•
this triggers impulses to be transmitted down neurone 2
(a) Using the information given above, explain why
(i)
such chemical transmission is one-way, from neurone 1 to neurone 2,
..................................................................................................................................
..............................................................................................................................[2]
(ii)
there is a small time-delay at each synapse.
..................................................................................................................................
..............................................................................................................................[1]
(b) State the evidence that you can see in Fig. 3.1 to suggest that the cell uses energy to
make the transmitter.
..........................................................................................................................................
......................................................................................................................................[1]
[Total: 4]
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4
Living bone consists of bone cells plus the matrix they secrete. The matrix consists of tough
collagen fibres and hard calcium salts. Fig. 4.1 shows what happens when a bone is treated
in two different ways.
soaked in acid
for several days
For
Examiner’s
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heated strongly
for several hours
bone has
become flexible
bone has
become brittle
G
H
Fig. 4.1
(a) Explain the changes seen in G and H.
G ......................................................................................................................................
......................................................................................................................................[2]
H ......................................................................................................................................
......................................................................................................................................[2]
(b) State two advantages of bone having living cells.
1. .......................................................................................................................................
2. ...................................................................................................................................[2]
[Total: 6]
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5
Fig. 5.1 shows the life cycle of Schistosoma, a blood fluke living in the blood vessels of the
human gut or bladder.
adults in the gut
or bladder wall
cercaria enters person
when drinking or
when swimming
fertilised eggs
in faeces or urine
first larval stage or miracidium
formed if eggs reach water
third larval stage or
cercariae in water
miracidia enter water
snail and form rediae larvae
that reproduce asexually
Fig. 5.1
(a) Using Fig. 5.1, suggest three ways to reduce the spread of the disease.
1. ......................................................................................................................................
2. ......................................................................................................................................
3. ..................................................................................................................................[3]
(b) Many people become infected around the ages of 5 or 6. Suggest why this may
happen.
......................................................................................................................................[1]
(c) Suggest why there are different larval stages in the life cycle.
..........................................................................................................................................
......................................................................................................................................[2]
[Total: 6]
© UCLES 2007
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For
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11
6
Fig. 6.1 is a diagram of the major blood vessels, S to Z, connecting the body organs.
head
S
RA LA
RV LV
lungs
T
Z
liver
key
RA
right atrium
LA
left atrium
RV
right ventricle
LV
left ventricle
U
Y
gut
X
kidney
capillaries
blood flow
trunk
W
V
Fig. 6.1
(a) Give the letter of the blood vessel labelled S to Z in Fig. 6.1 that contains the
(i)
(ii)
(iii)
(iv)
(v)
least urea,
most glucose after a meal,
least carbon dioxide,
most oxygen,
highest pressure.
.........................................
.........................................
.........................................
.........................................
.........................................
[5]
(b) Using only information from Fig. 6.1,
(i)
describe how the blood supply to the liver differs from that to the kidneys,
..............................................................................................................................[1]
(ii)
suggest a reason why the blood supply to the liver differs from that to the kidneys.
..................................................................................................................................
..............................................................................................................................[1]
[Total: 7]
© UCLES 2007
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7
Fig. 7.1 shows the sequence of events that take place in the blood when the skin is cut.
chemicals in damaged tissues
platelets burst open
activators
released
serotonin
released
calcium ions
arterioles constrict
elastic fibres
released making clot
contract
prothrombin (inactive enzyme)
thrombin (active enzyme)
fibrinogen
fibrin (trapping red cells)
clot forms
clot hardens
Fig. 7.1
(a) Using only information from Fig. 7.1, state the two end-results of this sequence that
help to prevent blood-loss.
1. ......................................................................................................................................
2. ..................................................................................................................................[2]
(b) Some people have low numbers of platelets. Give one reason why this will lengthen the
time it takes for their blood to clot.
......................................................................................................................................[1]
(c) Blood that is to be stored for use in later transfusions has its calcium ions removed and
is chilled.
How will these steps help to prevent clotting in storage?
1. removal of calcium ions ................................................................................................
......................................................................................................................................[1]
2. chilling ...........................................................................................................................
......................................................................................................................................[2]
[Total: 6]
© UCLES 2007
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Section B
Answer all the questions, including questions 8, 9 and 10 Either or 10 Or.
Write your answers on the separate answer paper provided.
8
(a) Describe how large quantities of sewage from a town are made harmless before discharge
into a river.
[11]
(b) Fig. 8.1 shows sections through two pit latrines, K and L.
L is an improved version of K.
concrete
concrete
1 metre
latrine K
latrine L
Fig. 8.1
List four ways in which latrine L differs from K. Explain why each difference is an improvement.
[4]
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9
(a) Using named examples, explain each of the following statements about hormones.
(i)
A hormone is made in one place in the body, but has its effects in another.
(ii)
Some hormones are quick-acting, while others are slow-acting.
(iii)
Some hormones operate all our lives, while others may have their effects for a period
only.
[10]
(b) Since hormones are powerful regulators of body chemistry, their levels in the body must
be carefully controlled. Fig. 9.1 shows how the amount of thyroxine, a hormone regulating
respiration, is controlled by the pituitary gland which monitors the concentration of thyroxine
in the blood. The pituitary gland secretes a hormone known as TSH (Thyroid Stimulating
Hormone).
pituitary gland
TSH (Thyroid Stimulating
Hormone) secreted
high levels of thyroxine
reduce activity
of pituitary gland
TSH stimulates growth
of the thyroid gland
and its secretion of thyroxine
thyroid gland
thyroxine
Fig. 9.1
Using Fig. 9.1, suggest what will happen in this system if thyroxine concentrations rise too
high.
[5]
10 Either
(a) The following substances are present in the blood. Describe what happens to each of these in
the kidney.
(i) protein (ii) glucose (iii) urea (iv) water.
(b) Explain how the kidney helps to save water if a person is sweating heavily.
[10]
[5]
10 Or
(a) State three similarities between the egg (ovum) and the sperm.
[3]
(b) State the differences between fertilisation and implantation.
[5]
(c) The placenta prevents maternal and fetal bloods from mixing. State why this is necessary. [3]
(d) Explain why mothers who smoke when they are pregnant are likely to have smaller babies.
[4]
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